Certain petroleum processing reactions run at high temperature have a tendency to produce unwanted coke, defined as impure carbon deposits or agglomerations, and depositing said coke on the walls of the reactors and associated pipes and valve systems. This coke deposition prevents proper thermal transfer from the tubes in a reactor or clogs up the pipes and valve openings associated with these reactors thereby necessitating a shutdown of the system in order to remove the unwanted coke deposits. In order to decrease the need for a shutdown of the petroleum process, antifoulants can be added by: (1) coating the metal surfaces prior to reaction, (2) dissolving said antifoulants into the petroleum feedstock to be processed, or (3) by suspending said antifoulants in said feedstock.